Effects of elevated ground temperatures on properties of cement grouts for deep rock grouting

Abstract

Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow. The behavior of grout, often highly temperature dependent, is likely to be affected by the elevated ground temperature in deep rock masses. This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting. The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8. When the temperature is up to 35°C, there can be significant improvements in rheological parameters, acceleration of grout setting, and increase in the rheological time dependence of thick cement grout; however, there may also be a slight impact on the initial grout flowability and the nature of shear thinning. The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably. The proposed constitutive model that couples the Burgers model with a fractional derivative‐based Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately. The paper provides a valuable reference for optimization of mixture design of cement grouts, thus enhancing deep rock grouting quality and improving safety.